Various kinds of biological information including an irregular biorhythm can be analyzed by continuously measuring a life activity. For example, Patent Document 1 discloses a technique in which information of a subject's activity can be obtained by attaching a body motion analyzing apparatus to the center of the waist in a predetermined direction. That is, in the technique disclosed in Patent Document 1, by attaching the body motion analyzing apparatus including a three-axis acceleration sensor to a waist in the predetermined direction, it is possible to detect a direction of the waist, and to distinguish whether the subject is bending down or lying. Further, in the technique disclosed in Patent Document 1, it is also possible to distinguish, from the frequency and the amplitude of AC components in an output signal of the acceleration sensor, whether the subject is walking or running.
Further, a method for estimating whether a subject is sleeping or awaking by detecting the intensity of body movement from information of the acceleration sensor attached to the subject's body has been conventionally used. Further, the most known acceleration sensor is a pedometer.
Further, physical and mental diseases can be estimated to some extent by using an apparatus for measuring a hormone in a brain and an apparatus for measuring a flow of blood. Further, body and mental disease can be estimated by conducting various tests and surveys.
For example, fatigue can be estimated by an ATMT method (Advanced Trial Making Test method). This ATMT method is a method for measuring a fatigue level based on how much time period it takes to touch numbers on a display one by one. Further, surveys are often conducted as a method for estimating physical and mental diseases including fatigue.
[Patent Document 1]
Japanese Unexamined Patent Application Publication Tokukaihei No. 7-178073 (published on Jul. 18, 1995)